This project focuses on gaps in our knowledge regarding molecular mechanisms by which platelets become pro-thrombotic in diabetes and in a key associated metabolic condition, obesity. Our studies have major clinical and translational significance because atherothrombosis and other thrombotic syndromes, including venous thrombosis and pulmonary embolism, are common and morbid complications of type 2 diabetes mellitus (DM) and obesity. Although the mechanisms have not been defined, there are substantial published observations indicating that platelets are hyperreactive and insulin resistant in these conditions. A central thematic hypothesis in the University of Utah Molecular Medicine Translational Research Center in Thrombosis (U2M2-TRCT), which we have established in response to this NHLBI initiative to develop translational programs in thrombotic and hemostatic disorders, is that changes in the systemic milieu of patients with metabolic syndromes leads to reprogramming of platelets, resulting in prothrombotic and dysfunctional activities. This hypothesis is based on extensive preliminary data generated from studies of human platelets and platelets in experimental models by U2M2-TRCT investigators. This project will examine the central hypothesis in subjects with type 2 DM and obesity, providing a rigorous test in the human model that complements pre-clinical studies in Projects 1 and 2 and additional novel clinical analysis in Project 4. Aim 1 will prospectively determine if platelet reprogramming occurs in type 2 DM and obesity, and Aim 2 will determine if reprogramming can be reversed by intervention with an agent with a unique therapeutic profile that has been extensively examined and used in the clinic, metformin. Our studies will provide critical translational observations that will be tightly integrated with discoveries in Projects 1, 2, and 4, and will also be an important vehicle for research career development activities of new and emerging translational investigators.